5G无线通信网络中英文对照外文翻译文献.docx

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1、5 G 无 线 通 信 网 络 中 英 文 对 照 外 文 翻 译 文 献(文 档 含 英 文 原 文 和 中 文 翻 译 )翻 译 ：5G 无线通信网络的蜂窝结构和关键技术摘 要第四代无线通信系统已经或者即将在许多国家部署。然而，随着无线移动设 备和服务的激增，仍然有一些挑战尤其是 4G 所不能容纳的，例如像频谱危机和 高能量消耗。无线系统设计师们面临着满足新型无线应用对高数据速率和机动性 要求的持续性增长的需求，因此他们已经开始研究被期望于 2020 年后就能部署 的第五代无线系统。在这篇文章里面，我们提出一个有内门和外门情景之分的潜 在的蜂窝结构，并且讨论了多种可行性关于 5G 无线通信

2、系统的技术，比如大量 的 MIMO 技术，节能通信，认知的广播网络和可见光通信。面临潜在技术的未 知挑战也被讨论了。介 绍信息通信技术（ICT）创新合理的使用对世界经济的提高变得越来越重要。 无线通信网络在全球 ICT 战略中也许是最挑剔的元素，并且支撑着很多其他的 行业，它是世界上成长最快最有活力的行业之一。欧洲移动天文台（EMO）报 道 2010 年移动通信业总计税收 1740 亿欧元,从而超过了航空航天业和制药业。 无线技术的发展大大提高了人们在商业运作和社交功能方面通信和生活的能力 无线移动通信的显著成就表现在技术创新的快速步伐。从 1991 年二代移动通信系统(2G)的初次登场到 2

3、001 年三代系统（3G）的首次起飞，无线移动网络已经 实现了从一个纯粹的技术系统到一个能承载大量多媒体内容网络的转变。4G 无 线系统被设计出来用来满足 IMT-A 技术使用 IP 面向所有服务的需求。在 4G 系 统中，先进的无线接口被用于正交频分复用技术（OFDM ），多输入多输出系统（MIMO）和链路自适应技术。4G 无线网络可支持数据速率可达 1Gb/s 的低流 度，比如流动局域无线访问，还有速率高达 100M /s 的高流速，例如像移动访问。 LTE 系统和它的延伸系统 LTE-A，作为实用的 4G 系统已经在全球于最近期或不 久的将来部署。然而，每年仍然有戏剧性增长数量的用户支持

4、移动宽频带系统。越来越多的人渴望更快的网络访问速度，时髦的手机，总的来说就是更快地与他人通信或信息访问。如今更多功能强大小巧的手机和便捷电脑可以满足先进的多媒体功能变 得越来越受欢迎。这就造成了无线移动设备和服务的激增。EMO 指出自从 2006年起，移动宽频每年有 92%的增长。无线世界研究论坛（WWRF）预言到 2017 年会有七万亿的无线设备来服务七十亿的人口；也就是说无线网络连接设备的数 量将会是世界人口数量的 1000 倍。随着越来越多的设备无线化许多研究难题需 要被解决。最重要的难题之一就是蜂窝通信中射频光谱分配的物质缺乏。蜂窝频率把极 高频带用于蜂窝手机，一般来讲范围可从几百兆赫

5、兹到几千兆赫兹。这些频谱被 严重的使用以至于对操作员更多的获取造成困难。另一个难题就是先进无线技术 的部署面临高能量消耗的费用。无线通信系统中高能消耗的增长间接造成了二氧 化碳排放量的增长，后者被视为当前生态环境的主要威胁。此外，据手机运营商 反映基站的能源消耗贡献了超过 70%的电力账单。事实上，节能通信并不是 4G 无线系统中的最初需求之一，但是它在之后的舞台上被作为问题所提及。其他的 难题，例如平均频谱效率、高传输率和高迁移率、无缝覆盖、多样化的服务质量 请求以及分散的用户体验（不同无线设备/接口的不兼容和异构网络），仅仅提及 一点点。以上所有问题正给手机服务提供商带来更多压力，他们正面

6、临着有更高传输 率、更大的网络容量、更高的频谱效率、更高的能源利用率和更高的利用率规定 的新型无线应用的持续增长需求。另一方面，在当前的技术条件下，4G 网络在 传输率方面几乎已经达到了理论上的限制，因此并不能充分的解决以上难题。从 这层意义上来说，我们需要开创性的无线技术来解决以上由数万亿无线设备造成 的问题，并且研究员们已经着手研究超 4G（B4G）或者 5G 无线技术。中英科学 桥工程：B4G 无线移动通信(http:/www.ukchinab4g. ac.uk/)可能是世界上着手 B 4G 研究的首批项目之一，其中的一些潜在的 B4G 技术已经被确定了。欧洲和中国 也 已 经 开 始

7、了 一 些 5G 项 目 ， 比 如 由 欧 盟 支 持 的 METIS 2020(https:/ www.metis2020. com/)和由中国科学院支持的在 5G 方面的国家 863 重点工程。诺基亚西门子通信公司描述通过对比 2010 年的通信水准今后十年潜 在的无线接入技术可以被进一步开发用来支持多大超过一千倍的通信量。三星公司展示了一个运用微波技术使传输率在两千米的范围内超过 1Gb/s 的无线系统。5G 网络，预期大约在 2020 年被标准化，究竟是什么呢？由于现在太早以至 于不能确切地定义。广泛的认同是与 4G 网络相比，5G 网络应该达到 1000 倍的 系统容量，10 倍的

8、频谱利用率、能源利用率和传输率（低流动性下最高传输率 为 10Gb/s，高流动性下最高传输率为 1Gb/s）还有 25 倍平均系统吞吐量。5G 网 络的目标在于连接整个世界以及实现任何人之间（人与人），任何事物之间（人 与机器，机器与机器）的无缝的、无处不在的通信，无论他们在哪，无论他们什 么时候需要，也无论他们用什么电子设备/服务/网络。这就意味着 5G 网络应该 能够支持一些 4G 网络所不能支持的特殊情况（例如乘坐高铁的用户）。高铁车 速可轻松达到 350 到 500km/h，然后 4G 网络所能支持通信的情况是 250km/h。 本篇文章中，我们提出了一个潜在的 5G 蜂窝结构并且讨论

9、有希望的技术用来部 署以便满足 5G 的需求。这篇文章剩下的安排如下。我们提出了一个潜在的 5G 蜂窝结构。我们描述 一些可行性的关键技术可以被 5G 系统采用。未来的挑战是显著的，最终我们会 得出结论。潜 在 的 5 G 无 线 蜂 窝 结 构为了解决以上难题并且满足 5G 系统的需求，我们需要在蜂窝结构的设计上 做个戏剧性的改变。我们知道无线用户 80%的时间都是待在户内，待在户外的仅 仅约有 20%。当前常见的蜂窝结构通常是为移动用户在蜂窝通信中间建立一个露 天基站，这样就不用管他们实在户内还是户外。对于户内用户与户外基站间的通 信，信号不得不穿过建筑墙，造成很高的穿透损耗，从而显著损伤

10、无线传输的传 输速率、频谱利用率、能源利用率。设计 5G 蜂窝结构的中心思想就是分开户内和户外的情况这样穿透损耗经过 建筑墙后可以在某种意义上来说避免掉。这些将会由分布式天线系统（DAS ）和 大量的 MIMO 技术来实现,即在地面上部署由几十个或几百个天线单组成的分布 式天线阵。然而目前最主流的 MIMO 系统使用两个或四个天线，大量使用 MIMO 系统的目的是为了开发尽可能大的容量效益以提升更大的天线阵。户外基站将会 装备由一些天线单元（也有大阵列天线）组成的大阵列天线，这些大阵列天线分 布在覆盖区周围，通过光纤连接基站，从而从 DAS 和大量的 MIMO 技术中都能受益。户外手机用户通常

11、配备有限数量的天线单元，但是他们可以通过互相合作形成一个虚拟的大阵列天线，连同基站天线阵将会构造虚拟的大规模 MIMO 链 接群。大阵列天线也将被安装在每个建筑的外面以便与户外基站群或者拥有分布 式天线单元的基站群相互通信，与可见组件通信也是有可能的。大阵列天线用电 缆连接到能与户内用户之间通信的建筑内部的无线接入点。这样必定会在短时间 内提高基础设备的花费最终显著提升覆盖区平均生产力，频谱效率，能源效率还 有蜂窝系统传输率。采用这样的蜂窝结构，户内用户仅需要使用安装在户外建筑 的大阵列天线便可与户内无线接入点通信，很多的技术可以被利用以便适用高数 据速率进行的短程通信。举一些例子包括 WiF

12、i，毫微微蜂窝，超宽频（UWB）， 毫米波通信（3300GHz），还有可见光通信(VLC)（400490THz）。值得 说明的是毫米波和 VLC 技术使用更高的频率并不适用传统的蜂窝通信。这些高 频波并不能很好地穿透固体材料并且很容易就会被气体，雨水还有植物吸收或分 散。因此，很难将这些波用于户外和远距离应用。然而，随着宽频带的实现，毫 米波和 VLC 技术可以大大提高在户内情况下的数据传输速率。为了解决频谱缺 乏问题，并且找到新的不为传统无线服务（例如毫米波通信和 VLC）所用的频 带，我们可以尽力提高现有无线频谱的频谱利用率，比如取道认识的无线网络。5G 蜂窝结构同样应该是一种有宏蜂窝，微

13、蜂窝，小基站和继电器组成的混 杂结构。为了适应高机动性用户比如乘车和乘高铁的用户，我们已经提出了超小 型移动基站的概念，即结合移动中继和超小型基站的概念。超小型移动基站位于 车辆内部可以和位于车内的用户通信，而大阵列天线位于车辆外面和户外的基站 通信。一个超小型移动基站和它关联的用户都被基站看作一个单元。从用户的角 度来看，超小型移动基站被看作正式的基站。这和上面区分户内（车辆内部）和户外情况的观点非常相似。已经能表明的是用户使用超小型移动基站 在享受高 数据速率的服务的同时减少信令开销。以上提出的 5G 混杂蜂窝结构在图 1 阐明。 有 前 景 的 5 G 无 线 网 络 的 关 键 技 术

14、在这一部分，基于以上提出的混杂式蜂窝结构，我们讨论了一些有前景的无 线网络关键技术使之能够满足 5G 无线网络的性能要求。发展这些技术的目的是 通过有效利用所有可能的资源以适应戏剧性的容量增长。基于著名的香农定理，s u m系统的总容量 C可以近似的表示为 (1)i其中 B 是第 i 条信道的带宽， Pi 是第 i 条信道的信号功率， Np 表示噪声功 率。从公式 1 可以看出系统总容量 C sum 等 于 所 有 子 通 道 和 网 路 容 量 之 和 。 为了增加Csum ，我们可以提高网络覆盖范围（通过使用含有宏蜂窝，微蜂窝，小基站，继 电器，超小型移动基站的网络），子通道的数量（通过使

15、用大量的 MIMO 技术， 空间调整，协作式 MIMO，DAS,管理干涉等等），带宽（通过 CR 网络，毫米波 通信，VLC，多标准系统等等）还有功率（能源利用率和绿色通信）。在下文中， 我们重点聚焦于一些关键技术。外文原文：ABSTRACTThe fourth generation wireless communica- tion systems have been deployed or are soon to be deployed in many countries. However, withan explosion of wireless mobile devices and se

16、r- vices, there are still some challenges that cannot be accommodated even by 4G, such as the spec- trum crisis and high energy consumption. Wire- less system designers have been facing the continuously increasing demand for high data rates and mobility required by new wireless applications and ther

17、efore have started research on fifth generation wireless systems that are expected to be deployed beyond 2020. In this article, we propose a potential cellular architec- ture that separates indoor and outdoor scenar- ios, and discuss various promising technologies for 5G wireless communication syste

18、ms, such as massive MIMO, energy-efficient communica- tions, cognitive radio networks, and visible lightcommunications. Future challenges facing thesepotential technologies are also discussed. INTRODUCTIONThe innovative and effective use of information and communication technologies (ICT) is becomin

19、g increasingly important to improve the economy of the world 1. Wireless communica- tion networks are perhaps the most critical ele- ment in the global ICT strategy, underpinning many other industries. It is one of the fastest growing and most dynamic sectors in the world. The European Mobile Observ

20、atory (EMO) reported that the mobile communication sector had total revenue of 174 billion in 2010, there- by bypassing the aerospace and pharmaceutical sectors 2. The development of wireless tech- nologies has greatly improved peoples ability to communicate and live in both business opera- tions an

21、d social functions.The phenomenal success of wireless mobile communications is mirrored by a rapid pace of technology innovation. From the second genera-tion (2G) mobile communication system debutedin 1991 to the 3G system first launched in 2001, the wireless mobile network has transformed from a pu

22、re telephony system to a network that can transport rich multimedia contents. The 4G wireless systems were designed to fulfill the requirements of International Mobile Telecom- munications-Advanced (IMT-A) using IP for all services 3. In 4G systems, an advanced radio interface is used with orthogona

23、l frequency-divi- sion multiplexing (OFDM), multiple-input multi- ple-output (MIMO), and link adaptation technologies. 4G wireless networks can support data rates of up to 1 Gb/s for low mobility, such as nomadic/local wireless access, and up to 100 Mb/s for high mobility, such as mobile access.Long

24、-Term Evolution (LTE) and its extension, LTE-Advanced systems, as practical 4G systems, have recently been deployed or soon will be deployed around the globe.However, there is still a dramatic increase in the number of users who subscribe to mobilebroadband systems every year. More and morepeople cr

25、avefaster Internet access on the move,trendier mobiles, and, in general, instant com- munication with others or access to information. More powerful smartphones and laptops are becoming more popular nowadays, demanding advanced multimedia capabilities. This has resulted in an explosion of wireless m

26、obile devices and services. The EMO pointed out that there has been a 92 percent growth in mobile broadband per year since 2006 2. It has been predicted by the Wireless World Research Forum (WWRF) that 7 trillion wireless devices will serve 7 billion people by 2017; that is, the number of network-co

27、nnected wireless deviceswill reach 1000 times the worlds population 4. As more and more devices go wireless, many research challenges need to be addressed.One of the most crucial challenges is thephysical scarcity of radio frequency (RF) spectra allocated for cellular communications. Cellular freque

28、ncies use ultra-high-frequency bands forcellular phones, normally ranging from severalhundred megahertz to several gigahertz. These frequency spectra have been used heavily, mak- ing it difficult for operators to acquire more.Another challenge is that the deployment of advanced wireless technologies

29、 comes at the cost of high energy consumption. The increase of energy consumption in wireless communication systems causes an increase of CO 2 emission indi- rectly, which currently is considered as a major threat for the environment. Moreover, it hasbeen reported by cellular operators that the ener

30、gy consumption of base stations (BSs) con- tributes to over 70 percent of their electricity bill 5. In fact, energy-efficient communication was not one of the initial requirements in 4G wire- less systems, but it came up as an issue at a later stage. Other challenges are, for example, aver- age spec

31、tral efficiency, high data rate and high mobility, seamless coverage, diverse quality of service (QoS) requirements, and fragmenteduser experience (incompatibility of differentwireless devices/interfaces and heterogeneousnetworks), to mention only a few.All the above issues are putting more pres-sur

32、e on cellular service providers, who are facing continuously increasing demand for higher data rates, larger network capacity, higher spectral efficiency, higher energy efficiency, and higher mobility required by new wireless applications.On the other hand, 4G networks have just about reached the th

33、eoretical limit on the data rate with current technologies and therefore are notsufficient to accommodate the above challenges. In this sense, we need groundbreaking wireless technologies to solve the above problems caused by trillions of wireless devices, and researchers have already started to inv

34、estigate beyond 4G (B4G) or 5G wireless techniques. The projectUK-China Science Bridges: (B)4G Wireless Mobile Communications (http:/www.ukchinab4g. ac.uk/) is perhaps one of the first projects in the world tostart B4G research, where some potential B4G technologies were identified. Europe and China

35、have also initiated some 5G projects, such asMETIS 2020 (https:/ www.metis2020. com/) sup- ported by EU and National 863 Key Project in5G supported by the Ministry of Science andTechnology(MOST) in China. Nokia SiemensNetworks described how the underlying radioaccess technologies can be developed fu

36、rther to support up to 1000 times higher traffic volumes compared to 2010 travel levels over the next 10 years 6. Samsung demonstrated a wireless sys- tem using millimeter (mm) wave technologies with data rates faster than 1 Gb/s over 2 km 7.What will the 5G network, which is expected to be standard

37、ized around 2020, look like? It is now too early to define this with any certainty.However, it is widely agreed that compared to the 4G network, the 5G network should achieve 1000 times the system capacity, 10 times the spectral efficiency, energy efficiency and data rate (i.e., peak data rate of 10

38、 Gb/s for low mobility and peak data rate of 1 Gb/s for high mobility), and 25 times the average cell through-put. The aim is to connect the entire world, andachieve seamless and ubiquitous communica- tions between anybody (people to people), any- thing (people to machine, machine to machine), where

39、ver they are (anywhere), whenever they need (anytime), by whatever electronic devices/services/netw orks they wish (anyhow). This means that 5G networks should be able to support communications for some special sce- narios not supported by 4G networks (e.g., for high-speed train users). High-speed t

40、rains can easily reach 350 up to 500 km/h, while 4G net- works can only support communication scenarios up to 250 km/h. In this article, we propose a potential 5G cellular architecture and discuss some promising technologies that can be deployed to deliver the 5G requirements.The remainder of this a

41、rticle is organized as follows. We propose a potential 5G cellular architecture. We describe some promising key technologies that can be adopted in the 5G sys- tem. Future challenges are highlighted. Finally,conclusions are drawn.A POTENTIAL 5G WIRELESS CELLULAR ARCHITECTURETo address the above chal

42、lenges and meet the 5G system requirements, we need a dramatic change in the design of cellular architecture. We know that wireless users stay indoors for about 80 percent of time, while only stay ourdoors about 20 percent of the time 8. The current conventional cellular architecture normally uses a

43、n outdoor BS in the middle of a cell communi-cating with mobile users, no matter whether they stay indoors or outdoors. For indoor users com- municating with the outdoor BS, the signals have to go through building walls, and this causes very high penetration loss, which significantly dam- ages the d

44、ata rate, spectral efficiency, and ener- gy efficiency of wireless transmissions.One of the key ideas of designing the 5G cel- lular architecture is to separate outdoor and indoor scenarios so that penetration loss throughbuilding walls can somehow be avoided. This willbe assisted by distributed ant

45、enna system (DAS)and massive MIMO technology 9, where geo- graphically distributed antenna arrays with tens or hundreds of antenna elements are deployed.While most current MIMO systems utilize twoto four antennas, the goal of massive MIMO systems is to exploit the potentially large capacitygains tha

46、t would arise in larger arrays of anten- nas. Outdoor BSs will be equipped with large antenna arrays with some antenna elements (also large antenna arrays) distributed around the cell and connected to the BS via optical fibers, bene- fiting from both DAS and massive MIMO tech- nologies. Outdoor mobi

47、le users are normally equipped with limited numbers of antenna ele- ments, but they can collaborate with each other to form a virtual large antenna array, which together with BS antenna arrays will construct virtual massive MIMO links. Large antenna arrays will also be installed outside of every bui

48、lding to communicate with outdoor BSs or distributed antenna elements of BSs, possiblywith line of sight (LoS) components. Large anten-na arrays have cables connected to the wireless access points inside the building communicating with indoor users. This will certainly increase the infrastructure cost in the short term while sig